In recent years, an on-vehicle device such as a car navigation device and a terminal device such as a smartphone are connected and used.
For example, Patent Reference 1 discloses a system in which a portable terminal and an on-vehicle device are cooperated and an application executed on the terminal device is operated from the on-vehicle device.
Non-Patent Reference 1 proposes a technique of transmitting a display image of a smartphone to an on-vehicle device to be displayed on a display unit of the on-vehicle device and operating an application on the smartphone by a touch input to the display unit of the on-vehicle device, by installing a dedicated module to the application installed in the smartphone.
When the display image of the smartphone is transmitted to the display device and displayed like Non-Patent Reference 1, the number of pixels and the aspect ratio of the display images are not necessarily the same between the smartphone and the display device. Therefore, according to the model of the smartphone, a black frame area is added at the top, bottom, left and right part of the outputted image in order to maintain the aspect ratio of the outputted image. Namely, the image displayed on the touch panel of the display device is the image created by adding the black frame area to the top, bottom, left and right part of the display image of the smartphone.
In this case, since the black frame area is included in the display image, the display device cannot discriminate whether or not the black frame area is being displayed. Therefore, when a part of the black frame area is touched on the touch panel of the display device, the smartphone may determine that the area within the display image is touched, although the touched area includes no button and the like. In addition, since the area of the image displayed on the touch panel of the display device does not coincide with the actual touch area, the coordinates of the point touched by a user may shift even inside of the black frame area.
In this view, the Patent Reference 2 discloses the method of preparing the calibration information for each combination of the smartphone and the display device and converting the input coordinates inputted by the user on the display device to the input coordinates of the smartphone based on the calibration information.